Reservoirs are commonly used to hold a liquid and are typically made by a blow molding process. For example, automotive fuel tanks hold fuel and are usually blow molded. In the automotive example, fuel lines are sometimes connected to fuel tanks for incoming and outgoing fuel, vapor lines are sometimes connected to fuel tanks for delivering vapor to a downstream charcoal canister, and other components can be connected to fuel tanks. The connections between fuel tanks, lines, and components often include connection components and welds. In particular, the connections sometimes involve cutting a hole in the reservoir, and welding or otherwise sealing a connection component around the periphery of the hole. While these connections may be effective, in some cases the connection components, welding, and cutting can add cost and complexity to the assembly, and may be vulnerable to leakage in the fuel tank.